Foam-producing apparatus



y 1950 w. J. CLIFFORD ETAL FOAM-PRODUCING APPARATUS Filed March 19 3 Sheets-Sheet l a a a y 1950 w. J. CLIFFORD ETAL I 25@@s227 FOAM- PRODUCING APPARATUS Filed March 19, 1945 3 Sheets-Sheet 2 y 195 w. J. CLIFFORD ET AL FOAM-PRODUCING APPARATUS 5 SheetsSheet 3 Filed March 19, 1945 Inventors patented May 16, 1 9 5 FOAM-PRODUCING APPARATUS V Wilfred James Clilford and Henry Howard Adams, Brentford, England, assignors to The Pyrene Company Limited, Brentford, England,-

a British company Application March 19, 1945, Serial No. 583,520

, In Great Britain March 27, 1944 8 Claims. (Cl. 261-94) This invention relates to the production of air foam by forcing water, a foam-forming liquid and air or other gas through a mixing body of the labyrinth type. As set forth in Clifiords application Serial No. 409,526, filed September 4, 1941, riowPatent No. 2,376,122, dated May 15, 1945, it is desirable for the water '(either mixed with or separate from the foam-forming liquid) tobe supplied under a constanthead that is independent of the pressure of the air or other gas. In the apparatusv described in said application No. 109,526 the constant head is produced by either an air-lift deviceor'a pump delivering to a vessel in which the liquid is maintained with a free surface under the same air or gas pressure as that applied to the mixing body, or the head is allowed to form by gravity under the control of a floatoperated valve. This apparatus is effective, but the former types are somewhat complex and the latter type takes up more space vertically than is desirable.

It is the primary object of this invention to provide a simpler and more compact form of apparatus for supplying the liquid under a constant head.

Another object of this invention is to provide an improved apparatus for producing foam for fire-extinguishing, dust-allaying or other purposes.

Fig. 1 is a schematic view intended to illustrate the principle of Mariottes bottle;

Fig. 2 is a view, largely in vertical section and partly in elevation, show-ing one form of apparatus embodying the present invention for the production of fire extinguishing foam; 'f: Fig. 3 is a schematic view of a modified form of apparatus embodying the invention, the tank forming part of this apparatus being shown only in part and in section; r

Fig. 41s a View similar to Fig. 3 showing a further embodiment of the invention;

Fig. 5 is a schematic view illustrating a still further embodiment of the invention, the tank forming part of the apparatus being shown in vertical section and other parts being only schematically indicated; and r -Fig. 6 is a view in vertical section through a-pparatus constituting still another embodiment of the invention.

, V 2 is immersed in water 4. This water can escape through an orifice 5 at the bottom under the con! trol of a valve 6. The pressure P at the orifice 5 does not vary with the level of the water in the container. The reason is that the pressure in the space above the water is the air pressure A (in cms. of water) less the distance H2 (in cms between the water level and the opening 3. The head at the orifice 5 is therefore AH2+H1,wher.e 1-11 is the distance between the water level and the orifice. But if H: is the distance 'betweenthe opening 3 and the orifice 5, H3=H1H2, so that P;A+Hz. ,Granted, therefore, that there is a constant pressure of air at the top of the tube Z and ,that the opening 3 is immersed'in water the pressure at the orifice will depend only on the dis-; tan'cebetween the'opening 3 and the orifice 5 In the production of apparatus-working in this principle in the present invention the waterofr solution of foam-forming liquid is placed in j'a closed tank or other container which corresponds to the closed vessel l, and is led directly to the mixing body from a point in the container at or near to the bottom. The air or other gas is not only led to the inletio the mixing body but also isintroduced through an opening' or openings above the point atwhich the liquid and gas meet on their way to the, mixing body but below the liquid level and low enough to ensure that most of the liquidwill run'o-ut of the containerbefore thelevel of the liquid falls to that'of the open ing or openings. The effective head H3 is the distance betweenthe opening ,or 'operiingsia'nd the point at which the liquid and'gas meet in flowing to the mixing body. The opening. or openings should be at only a short distance above the point at which the liquid and gas meetithat is to say, the distance H3 is preferably made small, because otherwise the opening or openings will be uncovered before most of the liquid has run out of the container. When the opening or openings are uncovered foam will continue to be formed until the inlet to the mixing body is uncovered, but the pressure will then no longer necessarily be constant; To ensure that the maximum amount of liquid is discharged under a constant head the liquid and gas should meet at asjlow a point in the container aspossible. The liquid below the inlet to the mixing body is not converted into 'ioam, so in order to utilise the contents of the container to the full the inlet to the mixing body should be as low as possible; The apparatus shown in Figurez comprisesa container [0 holding, for example, 200 gallons of water containing a foam-forming liquid in solution. A mixing body II, composed of randomly packed small pieces of metal tube or other appropriate material, is housed in a vertical tube I2 and supported at the lower or entrance end by a grid I3. A second tube I4 surrounds the tube I2. Both tubes extend vertically through the container I and out through the top of it. Air is introduced into the space between the tubes through a pipe I5 controlled by a valve I6. Openings I! are made in the tube I4, and are shrouded by a hood or bell I8 secured to the tube I4. The lower edge of this hood or bell lies far enough below the row of openings I! to provide an air lock through which the air can pass into the main part of the container.

The tube I4 is open at its lower end and has an inturned flange I9, and liquid passes from the body of the container through the aperture within this flange. A foam-discharge pipe 20 is connected to the upper end of the tube I2.

In operation air under pressure is supplied through the pipe I5 and the bulk of it flows down thespace between the tubes I2 and I4 to the bot tom and then turns upwards and ficws through the mixing body. Some of the air, however, passes through the openings I! under the lower edge'of the bell I8 into the body of liquid to rise into the space above. It will be seen that in this apparatus the distance H is that between the lower edge of the bell I18 and the point just above the aperture at the bottom of the tube I4 where the liquid and air meet to flow into the tube I2.

In the modification shown in Figure 3, the mixing body II is outside and below the container I0. Itis housed in a bent tube 2I which extends upwards for a short distance through the bottom of the container. The liquid flows from the contamer I0 through a row of apertures 22 made in thetube 2I just above the bottom of thecontainer. The air is introduced through a'pipe 23 which enters the pipe 2I and then is bent to run QQQXiaIly with the vertical part of it, terminating just short of its open end. This open end of the pipe 2| is shrouded by a bell or hood 24.

The modification shown in Figure 4 closely resembles that of Figure 2 and difiers only in that the lower ends of the tubes I2 and I4 lie in a well 25fwhich extends below the general level of the bottom of the container I2.' With this arrangemerit the whole volume of the liquid in the container except only that in the well can be con- Yitcd into foam, and as the bell I8 lies only just above the bottom of the container substantially all the foam will be delivered under constant pressur 7 "Figure 5 shows an apparatus suitable for producing foam for allaying the dust which arises diiring rock-drilling operations. For this purpose the total volume of foam required. is relatively small, and a container 26 of, say, five gallons'capacit'y, is used. The mixing body Ilis arranged in a tube I2 in the same way as in Figure Zland is surrounded by a tube I4 which carries an airv bell I8. In this apparatus it is convenient to" be able to vary the flow of liquid to the mix? ingbody and this is done by providing a conical valve 21 on the end of a spindle 28 which extends axially through the mixing body and is provided with an operating knob or handle 29 outside'the mixing body. Naturally the size of an aperture through which the liquid flows to the mixing body can be controlled in the other apparatus in the same way if desired.

' "Another way of controlling the flow, oi liquid is to vary the height of the column of liquid which is added to the air pressure to give the constant head, and this may be done by providing a series of openings with a sleeve valve or the like for uncovering whichever is desired or by making an air bell or hood vertically adjnstable. One such apparatus is shown in Figure in which a tube 36 terminates at the same level as a tube I2 containing the mixing body II and carries an air bell 31 formed with openings 33 at different levels. A cup-shaped member 39 fits inside the air bell 31 and is formed with openings 40 at levels corresponding to those of the openings 38 but spaced aroundthe member 39 so that in difierent angular positions of the air bell 31 and member 40 openings at different levels are brought into register with one another. The number 39 is formed with apertures 4I through which liquid can flow from the interior of the container I0 to the mixing body II and it is fixed to a spindle 42 which extends vertically through the mixing body. lhe spindle 42 is provided with an operating knob 43 by which it can be turned to vary the angular position of the member 3 9w'ithin the'air bell 3'1 and thus to. bring the desired opening 38 into register with the desired opening 40. By this means the distance H can be increased and the distance H3 correspondingly decreased from those shown in Figure 6.

It will be understood that in all the apparatus the passage ways for the air or other gas are made large enough to ensure that for practical purposes the pressures at the point where the liquid and gas streams meet and at the air bell are the same as that at the gas inlet.

A fire extinguishing apparatus such as that shown in Figure 2 is usually discharged only once, and then the discharge is continuous. For purpose of allaying' dust, however, an apparatus capable of being stopped and restarted is required. Now if the main foam outlet valve (not shown is turned off to stopthe flow, the pressure in the apparatus will increas above that normally occurring during running. When the outlet valve is opened again, the pressure acting upon the mixing body will not be that produced by the constant head alone, but also that of the excess oi the pressure in thespace above the liquid over the pressure in the remainder of the apparatus, which will have fallen to the running pressure: Accordingly in such an apparatus as thatshown in Figure 5 it is desirable to provide a bleeding valve in the space above the liquid, asshown at 3B. This valve is set to allow air to escape continuously and its opening is small in relation to the air passage ways, so that in normal operation it does not produce any reduction in the pressure in the space above the liquid, but when the foam outlet valve is closed it does serve to preventsuch an increase in pressure as would materially affect the operation of the apparatus.

We claim:

1. Apparatus for producing foam which comprises a closed sto'rage tank adapted to retain a foam forming solution, a labyrinth type mixing chamber in said tank, gas retaining meanssur rounding said mixing chamber, means for introducin o io om sa d t n n o aid m xin chamber, means for supplying gasunder pres. sure to said gas retaining means, means, for delivering gas from said retaining means in part. to said tank and in part to. said mixing chamber, said last mentioned means including a cup mem-. ber o a i with sa d ix g chambera d id s retain ng means t d ct e gas a ong.

the two paths indicated, and means for delivering foam formed in said mixing chamber to a point exterior of the tank.

2. Apparatus for producing foam which comprises a closed storage tank adapted to retain a foam forming solution, said tank having an outlet port adjacent its bottom, means for introducing a gas under pressure into the solution in said tank at a point at a predetermined level above said outlet port, a labyrinth type mixing chamber, means for delivering solution through said outlet port to said mixing chamber, means for varying the level at which said gas is introduced into the solution in said tank and thereby varying the rate at which said solution is delivered to said mixing chamber, and means for introducing gas under pressure into said chamber.

3. Apparatus for producing foam which comprises a closed storage tank adapted to retain a foam forming solution, a tubular member extending into the bottom of said tank, said member being apertured at a point within said tank adjacent its bottom for the discharge of solution from said tank, a mixing chamber connected with said member and arranged to receive the solution therefrom, and means for delivering gas under pressure through the interior of said tubular member, said member being open at its upper end and having a bell shrouding the same, the arrangement being such that a portion of the gas delivered by said means is enabled to pass from said bell into the solution and a portion of said gas is directed into said member and said mixing chamber.

4. Apparatus for producing foam which comprises a closed storage tank adapted to retain a foam forming solution, said tank having an outlet port for said solution adjacent its bottom, a gas supply means, means for introducing a gas under pressure from said supply means into the solution in said tank at a point below the upper surface thereof at a predetermined level above said outlet port, a labyrinth type mixing chamber, means for delivering solution discharged through said outlet port to said mixing chamber, and means for introducing gas from said supply means under pressure directly into said outlet port, said last recited means being arranged to provide a gas retaining enclosure around said outlet such that the gas therein opposes the flow of solution to said outlet.

5. Apparatus for producing foam which comprises a closed storage tank adapted to retain a foam forming solution, said tank having an outlet port adjacent its bottom, a gas retaining member, means for introducing a gas under pressure from said member into the solution in said tank at a point at a predetermined level above said chamber in said tank, a gas retaining member surrounding said mixing chamber, means adjacent the bottom of said tank for placing the solution in said tank in communication with said mixing chamber, means for supplying gas under pressure to said gas retaining member, means for delivering gas from said retaining member in part to the solution in said tank at a point above said first mentioned means and in part to said mixing chamber, and means for delivering foam formed in said mixing chamber to a point exterior of the tank.

7. Apparatus for producing foam which comprises a closed storage tank adapted to retain a foam forming solution, said tank having an outlet port adjacent its bottom, gas supplying means, means for introducing a gas under pressure from said supply means into the solution in said tank at a point above said outlet port, a labyrinth type mixing chamber, means for delivering solution from said tank through said outlet port to said mixing chamber, means for varying the rate at which said solution is delivered to said mixing chamber, and means for introducing gas under pressure into said chamber, said last recited means providing a partial enclosure in association with said outlet port in which said solution and gas are brought together.

8. Apparatus for producing foam which comprises a closed storage tank adapted to retain a foam forming solution and having a gas space above the solution, said tank having an outlet port adjacent its bottom, gas supply means, means including 2, gas receiving member connected with said supply means for introducing a gas under pressure into the solution in said tank at a predetermined level in relation to said outlet port, a labyrinth type mixing chamber, means for de livering solution through said outlet port to said mixing chamber, said last recited means providing a partial enclosure in association with said outlet port, means for introducing gas under pressure from said supply means to said partial enclosure and into said mixing chamber, means operable at will for varying the character of the foam and the rate at which it is discharged from said mixing chamber, and means for relieving the pressure within said gas space when the pressure therein rises above a predetermined amount.

WILFRED JAMES CLIFFORD. HENRY HEWARD ADAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,457,895 Campanella June 5, 1923 1,889,236 Burmeister Nov. 29, 1932 1,995,215 Mehlsen et a1 Mar. 19, 1935 FOREIGN PATENTS Number Country Date 117,253 Great Britain May 15, 1918 488,168 Great Britain July 1, 1938 661,376 Germany June 17, 1938 

